Using a very original study design, Goldstein et al1 report on the impact of the introduction of a rapid D-dimer assay on resource utilization for the diagnosis of pulmonary embolism (PE) in their institution. They randomized 4 firms of their hospital into 2 groups. In the intervention group, house staff and attending physicians were instructed on the use of D-dimer assay to rule out PE and encouraged to use it. In the control group, physicians were simply informed of the study protocol and asked to investigate PE in the traditional manner. In sharp contrast to the results expected by Goldstein et al, that the use of the D-dimer assay would reduce the number of diagnostic tests for PE,2,3 they observed a significant increase in the absolute number of patients investigated for suspected PE in the intervention group (304 of 2690 admitted patients [11.3%] vs 166 of 2700 patients [6.2%] in the control group). Furthermore, although the percentage of lung scans ordered was lower in the group using D-dimer assay as a first-line test (64% vs 81%), the absolute number of ventilation-perfusion scans performed was significantly higher than in the control group (194 vs 135). They concluded that easy access to a simple blood test increased resource utilization for suspected PE.